Organic compound hydrogenation apparatus and method for hydrogenating organic compound

ABSTRACT

An organic compound hydrogenation apparatus  1  of the present invention includes a reaction cell  13  to which an electrolytic solution is supplied, and an anode  11  and a cathode  12  arranged in the reaction cell  13 , in which the cathode  12  is made of a material including a hydrogen storage material, the cathode being arranged as a tubular member so that an organic compound as an object to be treated circulates thereinside. The present invention having the arrangement described above can provide a method for hydrogenating organic compounds and an organic compound hydrogenation apparatus that can enhance efficiency of hydrogenation of the organic compound.

TECHNICAL FIELD

The present invention relates to an organic compound hydrogenationapparatus for conducting hydrogenation of an organic compound, and amethod for hydrogenating the organic compound.

BACKGROUND ART

Conventionally, hydrogenation (hydrogenating) reaction of an organiccompound and the like has been utilized in various chemical fields and,for example, such hydrogenation reactions are actually utilized ascracking reaction of petroleum in which heavy oil is hydrogenated toobtain gasoline or kerosene and tar fraction is hydrogenised so that itis liquefied to be matched for more purposive use conditions. Further,hydrogenation is utilized in a reaction in which an unsaturatedhydrocarbon is converted into a corresponding saturated hydrocarbon, anda reaction in which a halogenated compound is dehalogenated.

In addition, as a method for performing hydrogenation reaction safelyand efficiently, there has been known a method in which an organiccompound is brought in contact with a metal capable of holding hydrogensuch as palladium and hydrogen storage metal alloy.

Further, the aforementioned palladium and many types of hydrogen storagemetal alloy have catalysis, and since hydrogen in palladium or otherhydrogen storage metals has strong reactivity as active hydrogen, it issaid that the palladium and the like function as a hydrogen-supplysource and hydrogenation catalyst to exert high function as a method forhydrogenating organic compounds.

However, in the hydrogenation reaction which uses palladium or hydrogenstorage metal alloy, since amount of hydrogen that can be absorbedthereinto is limited, there is such a defect that the stored hydrogen isconsumed along with progress of the reaction and further reaction doesnot proceed, thereby allowing only so-called a batch system reaction toproceed. Thus, although there is no problem in a laboratory scaleoperation, continuous operation is impossible in industrial scales,thereby resulting in much inefficiency.

In order to solve the above-described problem, there are proposed amethod in which by using a reaction cell having an anode and a cathodeformed in a division plate-like shape and made of a hydrogen storagematerial, electrolysis is conducted, while allowing an organic compoundto contact with the cathode surface on a side not facing the anode, andthen active hydrogen generated at the cathode is absorbed and penetratesthe cathode to the side not facing the anode to hydrogenate the organiccompound; and a technique regarding a reaction cell (Japanese PatentLaid-open Application Publication No. 9-184086).

However, with the aforementioned technique, since a large effectivecontact area can be obtained between the division plate-like cathode andorganic compounds, efficiency of hydrogenation of an organic compound isstill insufficient.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a method forhydrogenating an organic compound and an organic compound hydrogenationapparatus which are capable of enhancing efficiency of hydrogenation ofthe organic compound.

In order to achieve the above-described object, an organic compoundhydrogenation apparatus according to an aspect of the present inventionfor hydrogenating an organic compound includes: a reaction cell to whichan electrolytic solution is supplied; and an anode and a cathodearranged in the reaction cell, in which the cathode is made of amaterial including a hydrogen storage material, the cathode beingarranged as a tubular member so that the organic compound as an objectto be treated circulates thereinside.

Here, as for the anode, platinum, carbon, nickel, stainless-steel andthe like can be exemplified. The cathode may be any tubular members,which have a polygonal cross section such as triangle, tetragon orpentagon, or may have a circular or ellipsoidal cross section. Aplurality of tubular members may also be used.

As for the hydrogen storage material, palladium, palladium alloy such aspalladium-sliver alloy, rare-earth metal alloy such as lanthanum-nickelalloy, misch metal-nickel alloy, titanium, zirconium alloy and the likecan be exemplified.

In addition, in order to allow the hydrogenation reaction in the tubularcathode to proceed smoothly, it is preferable that a contact areabetween the organic compound and the inner surface of the cathode issufficiently large, and thus desirably the surface of the contactportion is sufficiently roughened.

In order to roughen the inner surface of the tube of the cathode, blasttreatment or etching treatment is desirable. Although a degree oftreatment is not particularly limited, the blast treatment is preferablycarried out by using an alumina grid having around 15 to 20 meshes,whereby substantial surface area becomes 2 to 3 times.

There is no particular limitation for a reaction cell as long as it hasa size and shape that can incorporate the anode and cathode.

The electrolytic solution with which the reaction cell is filled is notparticularly limited as long as the solution generates hydrogen from thecathode at the time of the electrolysis. For instance, potassiumhydroxide, sodium hydroxide and the like can be exemplified a basicelectrolytic solution. Also, aqueous sulfuric acid solution, aqueoushydrochloric acid solution and the like can be exemplified as an acidicelectrolytic solution.

Reactions generated in the electrolytic solution upon the electrolysiswill be described below. When the electrolytic solution is a basic onesuch as an aqueous potassium hydroxide solution or aqueous sodiumhydroxide solution, or is a neutral one, the reaction formula is asshown below in Formula (I).H₂O+e⁻→Had+OH⁻  (I)

When the electrolytic solution is an acidic one such as an aqueoussulfuric acid solution, an aqueous hydrochloric acid solution, or thelike, the reaction formula is as shown below in Formula (II).H⁺+e⁻→Had  (II)

In these Formulae (I) and (II), Had is adsorbed hydrogen and, thereaction according to the above Formula (I) or (II) occurs on theoutside surface of the cathode contacting with the electrolyticsolution. The Had in Formulae (I) and (II) is held on the outsidesurface of the cathode in an adsorbed state. The adsorbed hydrogen isconverted into a state absorbed in the cathode, as represented byfollowing Formula (III) below.Had→Hab  (III)

In Formula (III), Hab is an absorbed hydrogen. The Hab in Formula (III)reacts with the organic compound supplied inside the cathode tohydrogenate the organic compound.

Hydrogen which has been absorbed in the cathode is consumed only whenthe cathode contacts with the organic compounds so that hydrogenation ofthe organic compound occurs. A consumed amount of hydrogen is producedalong with the progress of the reaction, and is absorbed in the cathode,thereby leading to a state in which hydrogen is constantly absorbed inthe cathode in an amount close to the maximum absorption amount.

The hydrogenation reaction of the organic compound according to thepresent invention includes reduction reaction of aliphatic or aromaticunsaturated hydrocarbons having a double bond or a triple bond such asethylene, propylene, 1-octene or 2-octene, acetylene, styrene andquinone into corresponding saturated hydrocarbons, the reactiongenerating ethane, propane, n-octene (Translator's comment: correctly,n-octane), ethane, ethylbenzene and hydroquinone, respectively.

Further, the hydrogenation reaction of the organic compound according tothe present invention also includes dehalogenation reaction ofhalogenated aromatic compounds such as 2-chlorophenol, 4-chlorotolueneand dioxins, the reaction generating phenol, toluene and dehalgenatedcompounds of dioxins, respectively.

Examples of the halogenated compound include halogenated aromaticcompounds and halogenated aliphatic compounds, and examples of halogeninclude fluorine, chlorine, bromine and iodine.

Furthermore, a bond of long chain hydrocarbon such as paraffin also canbe broken by hydrogenation to generate two or more types of short chainhydrocarbon (cracking). In addition, the present invention can beapplied to generate benzyl alcohol by hydrogenation of benzaldehyde andto generate nitrosobenzene or aniline by hydrogenation of nitrobenzene.

The organic compound to be treated is not necessarily in liquid form,but may be in gaseous or solid form. In the case of gaseous form, gas ispassed through the cathode as pressurized gas as it stands or by beingpressurized. In order to allow the reaction to proceed better, gas maybe blown into the cathode. In the case of solid, it may be suspended ina solvent to be brought in contact with the cathode, or may be made intopowder and blown as it stands into the cathode.

According to the present invention described above, since the cathode ismade of a material including a hydrogen storage material, and isarranged as a tubular member so that the organic compound as an objectto be treated circulates inside, conducting electrolysis in a reactioncell filled with an electrolytic solution results in generation ofhydrogen on the outer surface of the cathode, and the generated hydrogenis absorbed in the tube wall of the cathode. Then, since the organiccompound circulating inside the tube is in a state surrounded by thetube wall of the cathode, it can easily contact with the tube wall inwhich hydrogen is absorbed, so that a contact area effective forhydrogenation of organic compounds becomes larger as compared to that ofa conventional cathode having a division plate-like shape or the like,thereby enhancing the efficiency of hydrogenation of the organiccompound.

The cathode may also be formed on a support by coating or the like.

In the organic compound hydrogenation apparatus according to the presentinvention, it is preferable that the hydrogen storage material ispalladium.

With the arrangement, since palladium has very high hydrogenpermeability and, has a catalytic activity for hydrogenation, it issuitable for the hydrogen storage material for use in the presentinvention.

In the organic compound hydrogenation apparatus according to the presentinvention, it is preferable that the cathode is formed by providingsurface treatment on an inner surface of the tubular member with thehydrogen storage material.

Here, example of the surface treatment of the hydrogen storage materialon the inner surface of the cathode includes a surface treatment methodin which palladium black is formed on the inner surface of the cathodeby electrolytic reduction treatment of palladium chloride.

With the arrangement, since the hydrogen storage material itself acts asa catalyst upon hydrogenation reaction of the organic compound, reactionrate of the hydrogenation reaction can be enhanced further.

In the organic compound hydrogenation apparatus according to the presentinvention, it is preferable that the cathode is formed by filling thetubular member with the hydrogen storage material.

Here, as for the form of the hydrogen storage material, in addition tohydrogen storage material having a shape of powder or fiber, a form inwhich the hydrogen storage material is supported or coated on variouscarriers having the shape can be used.

With the arrangement, since the hydrogen storage material has a largesurface area, which increases an area where the organic compoundcontacts effectively with hydrogen, reaction rate of the hydrogenationreaction can further be enhanced.

As for the carrier, those used for usual catalysts can be exemplified,including silica, alumina, silica-alumina, activated carbon, carbonfiber and the like.

A method for hydrogenating an organic compound according to anotheraspect of the present invention to hydrogenate the organic compoundincludes the steps of: by using a reaction cell having an anode and atubular cathode made of a hydrogen storage material, applying voltagebetween the anode and the cathode to electrolyze an electrolyticsolution existing between the anode and the cathode; and circulating theorganic compound as the object to be treated inside the tubular cathodeto hydrogenate the organic compound.

According to the present invention described above, by electrolyzing theelectrolytic solution existing between the anode and cathode, whilecirculating the organic compound as an object to be treated inside thetube of the cathode, hydrogen is generated on the outer surface of thecathode and the generated hydrogen is absorbed in the tube wall of thecathode. Further, since the circulating organic compound is in a statesurrounded by the tube wall of the cathode, it can easily contact withthe tube wall in which hydrogen has been absorbed, and the contact areaeffective for hydrogenation of the organic compound becomes larger ascompared to the conventional division plate-like cathode and the like,thereby enhancing the efficiency of hydrogenation of the organiccompound.

In the method for hydrogenating the organic compound according to thepresent invention, feed rate of the organic compound is preferablycontrolled as needed in accordance with status of the reduction.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing a hydrogenation apparatus accordingto an embodiment of the present invention;

FIG. 2 is a table showing a relation between electrolysis current valueand cell voltage when surface area of an electrolysis cell is 8 cm² andan electrolytic solution is a 0.3 M aqueous sulfuric acid solution;

FIG. 3 is a table showing measurement conditions and measurement resultsin Examples 1 to 5;

FIG. 4 is a table showing measurement conditions and measurement resultsin Examples 6;

FIG. 5 is a table showing measurement conditions and measurement resultsin Examples 7 and 8 and Comparison 2; and

FIG. 6 is a graph showing relation of the number of cycles and remainingratio of remaining chlorinated aromatic compound.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below withreference to the attached drawings.

FIG. 1 shows a hydrogenation apparatus 1 of an organic compoundaccording to the embodiment of the present invention.

The hydrogenation apparatus 1 is a hydrogenation apparatus forhydrogenating an organic compound, which includes a cylindrical reactioncell 13 having therein an anode 11 and a cathode 12 made of a materialincluding a hydrogen storage material, a power source 14 for applyingvoltage to the anode 11 and cathode 12, an electrolytic solution pump 15for supplying an electrolytic solution into the reaction cell 13, anelectrolytic solution reservoir 16, an organic compound pump 17, and anorganic compound reservoir 18.

Examples of the organic compound as an object to be treated includeliquid aliphatic or aromatic unsaturated hydrocarbons having a doublebond or a triple bond such as ethylene, propylene, 1-octene and2-octene, acetylene, styrene, quinones, paraffins, benzaldehyde andnitrobenzene.

Also, halogenated aromatic compounds such as 2-chlorophenol,4-chlorotoluene and dioxins may be used as the organic compound as theobject to be treated, the halogenated aromatic compounds being subjectedto dehalogenation reaction.

The cathode 12 is formed by a tubular member made of palladium, whichdivides the inside of the reaction cell 13 into an electrolytic chamber13A and a hydrogenation chamber 12A (each described later) andpenetrates the cylindrical reaction cell 13 along a central axis thereofand the organic compound as the object to be treated circulates insidethe tubular member. An internal space of the tubular member is definedas the hydrogenation chamber 12A.

Palladium black is formed on an inner surface of tubular member of thecathode 12 by electrolysis reduction treatment of palladium chloride.

Further, surface roughening treatment is provided to the inner surfaceof tubular member of the cathode 12. Blast treatment, etching treatmentand the like can be exemplified as the surface roughening treatment.

The reaction cell 13 is a cylindrical member with upper and lower sidesthereof being closed with platy members, to which the electrolyticsolution is supplied. A space excluding the cathode 12 in the reactioncell 13 defines the electrolytic chamber 13A. A discharge port 131 and asupply port 132 each corresponding to the inner diameter of the cathode12 are formed at the centers of the platy members on the upper and lowersides of the reaction cell 13 for discharging and supplying the organiccompound.

A discharge port 133 and a supply port 134 for discharging and supplyingan electrolytic solution are provided at a radially-outer part from thecenter of the platy member on the lower side of the reaction cell 13.

A gas exhaust port 135 for exhausting gas generated from theelectrolytic solution in the reaction cell 13 upon electrolysis isprovided at a radially-outer part from the center of the platy member onthe upper side of the reaction cell 13.

Although not shown, these discharge port 131, supply port 132, dischargeport 133, supply port 134 and gas exhaust port 135 can be arbitrarilyopened and closed by valves or the like.

The reaction cell 13 is filled with the electrolytic solution. Theelectrolytic solution is aqueous sulfuric acid solution of 0.01 to 10 N(normal).

When the concentration of the aqueous sulfuric acid solution is lessthan 0.01 N, sometimes an efficiency of electrolysis is low and thus theamount of the generated hydrogen becomes small, which is insufficientfor continuously hydrogenating organic compounds.

On the other hand, when the concentration of an aqueous sulfuric acidsolution exceeds 10 N, sometimes material cost increases, becausesulfuric acid that produces hydrogen of more than a limit amountrequired for the hydrogenation is consumed.

The power source 14 is a voltage variable power source. A positiveelectrode of the power source 14 is connected to the anode 11, while anegative electrode of the power source 14 is connected to the cathode12.

The electrolytic solution pump 15 supplies the electrolytic solutionstored in the electrolytic solution reservoir 16 into the reaction cell13 via the supply port 134. Although not shown, a valve or the like maybe provided between the electrolytic solution pump 15 and the supplyport 134.

The organic compound pump 17 supplies the organic compound stored in theorganic compound reservoir 18 into the cathode 12 via the supply port132. Although not shown, a valve or the like may be provided between theorganic compound pump 17 and the supply port 132 to control feed rate ofthe organic compound.

A method for hydrogenating the organic compound using the hydrogenationapparatus 1 will be described below.

First, by actuating the electrolytic solution pump 15, the electrolyticsolution stored in the electrolytic solution reservoir 16 is suppliedinto the electrolytic chamber 13A of the reaction cell 13 via the supplyport 134. After checking that the electrolytic chamber 13A is filledwith the electrolytic solution, the power source 14 is actuated to applyvoltage between the anode 11 and cathode 12.

At this time, the voltage applied between the anode 11 and cathode 12 isnot particularly limited but, from the point of the apparatus, 0.1 to100 V is preferable.

In the electrolytic solution, electrolysis starts, and since theelectrolytic solution is aqueous sulfuric acid solution which is acidic,reactions described below occur on contact surfaces of the anode 11 andcathode 12 contacting with the electrolytic solution. A reactionrepresented by Formula (IV) below occurs on the anode 11.2H₂O→O₂+4H⁺+4e⁻  (IV)

A reaction represented by Formula (V) below occurs on the cathode 12.H⁺+e⁻→Had  (V)In Formula (V), Had is adsorbed hydrogen. The Had in Formula (V) is heldon the outer surface of cathode 12 in an adsorbed state. The adsorbedhydrogen is converted into an absorbed state on a tube wall of cathode12 as represented by Formula (VI) below.Had→Hab  (VI)

In Formula (VI), Hab is absorbed hydrogen.

After power distribution from the power source 14 starts andelectrolysis starts in the electrolytic solution, by actuating theorganic compound pump 17, the organic compound stored in the organiccompound reservoir 18 is circulated inside the tube portion of cathode12, that is, the hydrogenation chamber 12A via the supply port 132.

At this time, feed rate of the organic compound can be controlled byadjusting the organic compound pump 17.

Hydrogen absorbed in the cathode 12 (Hab in Formula (VI)) reaches thehydrogenation chamber 12A of the cathode 12, which reacts with theorganic compound supplied to the hydrogenation chamber 12A to reduce theorganic compound.

Incidentally, during conducting the electrolysis, O₂ and H₂ gas aregenerated in the reaction cell 13, as shown in above Formulae (IV) and(V). Therefore, the gas exhaust port 135 is appropriately opened andclosed to exhaust gasses of O₂ and excess H₂ gas that has not beenabsorbed.

As for a more specific method for hydrogenating unsaturated organiccompounds using the hydrogenation apparatus 1, for example, a followingmethod can be employed.

1 mmol of reaction substrate is dissolved in an organic solvent (such asmethanol or ethyl acetate) to prepare 10 ml of a 0.1 M solution.Pre-electrolysis is previously conducted (around 100 to 500 mA, 500 C)up to a state in which palladium black on the inner surface of thepalladium tube of the cathode 12 absorbs hydrogen sufficiently.Subsequently, electrolysis is conducted while circulating the preparedsolution inside the tube at various flow rates. Electrolysis currentvalue is suitably set while considering both of time period for reactionand current efficiency. When the reaction time is intended to be set asshort as possible, electrolysis is preferably conducted with a largecurrent value. However, in this case, current efficiency is lowered. Onthe other hand, when it is intended to conduct the reaction with anenhanced current efficiency, a small current value is selected. However,in this case, the reaction time increases.

Relation between the electrolysis current value and the cell voltage isas shown in FIG. 2 when, for instance, surface area of an electrolysiscell is 8 cm² and the electrolytic solution is a 0.3 M aqueous sulfuricacid solution.

According to the embodiment described above, following advantages can beobtained.

-   (1) Since the cathode 12 is made of a material including a hydrogen    storage material, and is arranged as a tubular member so that the    organic compound as the object to be treated circulates inside, when    electrolysis is conducted in the reaction cell 13 filled with the    electrolytic solution, hydrogen is generated on the outer surface of    cathode 12, and the generated hydrogen is absorbed in the tube wall    of cathode 12. Then, since the organic compound circulating inside    the tube is in a state surrounded by the tube wall of the cathode,    it can easily contact with the tube wall in which hydrogen is    absorbed, and a contact area effective for hydrogenating the organic    compound becomes larger as compared to that of a conventional    cathode having a division plate-like shape or the like. Thus, the    efficiency of hydrogenation of the organic compound can be enhanced.-   (2) Since palladium has very high hydrogen permeability, and a    catalytic activity for hydrogenation, it is suitable as the hydrogen    storage material for the cathode 12.-   (3) Palladium black is formed on the inner surface of the tubular    member of the cathode 12 by electrolysis reduction treatment of    palladium chloride, and since palladium black acts as a catalyst    upon hydrogenation reaction, reaction rate can be enhanced.-   (4) Since surface-roughening treatment is provided on the inner    surface of the tubular member of the cathode 12, substantial surface    area, thereby enhancing reactivity of hydrogenation reaction of the    organic compound.

Incidentally, the present invention is not limited to the aforementionedembodiment, and any variations and improvements are included in thepresent invention so far as the object of the present invention can beachieved.

Although platinum is used as the anode 11 in the aforementionedembodiment, carbon, nickel, stainless-steel or the like may also beused.

Although the tubular member having the circular cross section is used asthe cathode 12 in the aforementioned embodiment, the cathode 12 may havea polygonal cross section such as triangle, quadrangle and pentagon, ormay have elliptic cross section.

Although the cathode 12 is made of palladium in the aforementionedembodiment, the cathode 12 may be made of palladium alloy such aspalladium-silver alloy, rare-earth metal alloy such as lanthanum-nickelalloy, misch meta-nickel alloy, a titanium alloy or a zirconium alloy.

Further, the cathode 12 may be filled with hydrogen storage materialinside the tubular member.

Here, as for the form of the hydrogen storage material, in addition tohydrogen storage material having a shape of powder, fiber or the like, aform in which the hydrogen storage material is supported or coated onvarious carriers having the above-described shape can be used.

With the arrangement, the aforementioned hydrogen storage material has alarge surface area, which increases area where the organic compound andhydrogen contact effectively, thereby further enhancing reaction rate.

As for the carrier, those used for usual catalysts can be exemplified,including silica, alumina, silica-alumina, activated carbon, carbonfiber and the like.

Although the organic compound to be treated is in liquid form in theaforementioned embodiment, the organic compound may be in gaseous orsolid form. In the case of gaseous form, gas is passed through thecathode 12 as pressurized gas as it stands or after being pressurized.In order to allow the reaction to proceed better, gas may be blown intothe cathode 12. In the case of solid, it may be suspended in a solventand brought into contact with the cathode, or may be made into powderand blown as it stands into the cathode.

Specific configurations and profiles when implementing the presentinvention may be other configurations or the like as long as the objectof the present invention can be attained

The present invention will be described more specifically referring toExamples and Comparisons. However, the present invention is not limitedto the content of the Examples and the like.

EXAMPLES 1 TO 5

Hydrogenation reaction of an organic compound was conducted by using thehydrogenation apparatus 1 of the aforementioned embodiment.

(1) Modification of Inner Surface of Palladium Tube of Cathode 12 withPalladium Black:

Prior to hydrogenation reaction of the organic compound, palladium blackwas formed on an inner surface of a tubular member as the cathode 12 byelectrolysis reduction treatment of palladium chloride according to thefollowing procedure.

Around 100 to 300 mg of PdCl₂ was added to a 1 M aqueous hydrochloricacid (HCl) solution and stirred to dissolve to a maximum extent. Theprepared solution was circulated inside a palladium tube at a flow rateof 2.5 cm³/min using a pressure feed pump or a pump for liquidchromatography.

Electrolytic reduction was conducted using the palladium tube (innerdiameter 2.5 mm, length 8 cm) as a cathode at a constant current (80mA/cm⁻² to 500 mA/cm⁻²) (Translator's comment: correctly, 80 mA/cm² to500 mA/cm²) to modify the inside of the palladium tube with palladiumblack. At this time, hydrogenation reaction can be conducted moreeffectively by performing modification after filling the tube withcarbon fiber and the like.

(2) Hydrogenation Reaction of Organic Compound:

Each 1 mmol of unsaturated organic compounds shown in Entry of FIG. 2(Translator's comment: correctly, FIG. 3) was dissolved in ethyl acetateto prepare 10 ml of a 0.1 M solution. The hydrogenation apparatus 1 ofthe present invention was applied to the respective unsaturated organiccompounds shown in FIG. 2 (Translator's comment: correctly, FIG. 3)starting from the top column downward, which defines Examples 1 to 5 inthis order.

Using the hydrogenation apparatus 1, which is provided with a platinumwire as the anode 11 and a palladium tube having been modified accordingto method (1) as the cathode 12 in a 0.3 M aqueous sulfuric acidsolution, constant-current electrolysis (electrical flow 2 F/mol) wasconducted at 260 mA while flowing each of the prepared solutions ofExamples 1 to 5 into the palladium tube at a flow rate of 0.8 cm³/min bya pressure feed pump, and hydrogenation of the unsaturated organiccompound was conducted. A cell voltage at this time was about 2.9 V.

After the reaction ends, the solution was collected and concentratedand, finally, analyzed qualitatively/quantitatively with NMR, GC andGC-MS to obtain yield and current efficiency. The results are shown inFIG. 3.

EXAMPLE 6

Ethyl cinnamate was used as an unsaturated organic compound andhydrogenation was conducted under the same measurement conditions asthose in Examples 1 to 5. Then, yield and current efficiency wereobtained in the same way as described above. Measurement conditions andmeasurement results are shown in FIG. 4.

[Comparison 1]

Using a cell represented in the aforementioned patent document 1(Translator's comment: correctly, Japanese Patent Laid-open ApplicationNo. 9-184086), in which an electrolytic chamber and a hydrogenationchamber is divided by a palladium plate, hydrogenation reaction oforganic substance was conducted under the following conditions.

(1) Modification of Palladium Plate with Black Palladium:

A diaphragm type electrolysis cell was assembled using a palladium plate(effective surface area of about 2.2 cm²) having a thickness of 50 μm,which served both as a diaphragm and a cathode. The electrolytic chamberside was filled with a 0.3 M aqueous sulfuric acid solution, while thereaction chamber side was filled with 15 ml of a 28 mM PdCl₂ solutionprepared by dissolving 74 mg of PdCl₂ in a 1 M aqueous HCl solution.

Using a 2 cm×2 cm platinum plate as an anode, and a palladium plate ofthe aforementioned specification as a cathode, a constant-currentelectrolysis at 50 mA/cm² was conducted for 1 hour to deposit palladiumblack on the palladium plate surface of the reaction chamber side.

(2) Hydrogenation Reaction of Organic Compound:

Using the electrolysis cell having a specification similar to thatdescribed in the aforementioned patent document 1 (Translator's comment:correctly, Japanese Patent Laid-open Application No. 9-184086), to whichthe above-described treatment (1) had been provided, hydrogenationreaction of ethyl cinnamate was conducted according to the followingprocedure.

In the reaction chamber side, 10 ml of a 0.1 M solution was prepared bydissolving 1 mmol of ethyl cinnamate in ethyl acetate. Aconstant-current electrolysis was conducted at a current value of 260 mAand an electrical flow of 2 F/mol to hydrogenate ethyl cinnamate. A cellvoltage at this time was 2.4 V.

After the reaction ends, the solution was collected and concentratedand, finally, analyzed qualitatively/quantitatively with NMR, GC andGC-MS to obtain yield and current efficiency. Conditions and results atthat time are shown in FIG. 5.

[Evaluation Results]

As shown in FIG. 3, it was confirmed that the hydrogenation apparatus 1was able to hydrogenate various unsaturated organic compounds, and hadvery high yield and current efficiency, which was excellent.

Further, as shown in FIG. 4, it was confirmed that the hydrogenationapparatus 1 according to the present invention had very high yield andcurrent efficiency as compared to the conventional hydrogenationapparatus provided with the palladium plate even under the same reactionconditions, and that the hydrogenation apparatus was highly-effective ascompared to the conventional one.

Furthermore, an inner surface area of the palladium tube in Example 6was 7 cm² and the surface area of the palladium plate in Comparison was2.2 cm². Calculation of current efficiency per unit area based on thesesurface areas gave 13%/cm² for Example 6 and, on the other hand,4.5%/cm² for Comparison. From the result, it was confirmed that thehydrogenation apparatus 1 in Example 6 has a higher current efficiencyper unit area.

EXAMPLES 7, 8 AND COMPARISON 2

As one embodiment of hydrogenation reaction of chlorinated aromaticcompounds, 2-chlorophenol was dechlorinated and, at the same time,yield, current efficiency and current efficiency per unit area werecompared between conditions where a palladium tube electrode was usedand a palladium plate electrode was used.

(1-a) Modification of Inner Surface of Palladium Tube of Cathode 12 withPalladium Black:

For the palladium tube electrode used for the hydrogenation apparatus 1in Example 7, prior to dechlorination reaction of a chlorinated aromaticcompound, palladium black was formed on the inner surface of tubularmember of the cathode 12 by electrolytic reduction treatment ofpalladium chloride according to the following procedure as was the casewith Example 1.

That is, around 100 to 300 mg of PdCl₂ was added to a 1 M aqueoushydrochloric acid (HCI) solution and stirred to dissolve to a maximumextent. The prepared solution was circulated inside the tube at a flowrate of 2.5 cm³/min using a pressure feed pump or a pump for liquidchromatography.

By conducting electrolytic reduction while using the palladium tube(inner diameter 2.5 mm, length 8 cm) as a cathode at a constant current(80 mA/cm² to 500 mA/cm²) to modify the inside of the palladium tubewith palladium black.

(1-b) Modification of Inner Surface of Palladium Tube and Carbon FiberFilled in Palladium Tube with Palladium Black:

As for the palladium tube electrode used for the hydrogenation apparatus1 in Example 8, the tubular member of the cathode 12 was filled withcarbon fiber having a diameter of about 0.2 to 0.4 mm and a length ofabout 10 cm, then by using a method similar to (1-a), the palladium tubeelectrode in which the inner surface of the palladium tube and thecarbon fiber filled in the palladium tube were modified with palladiumblack was obtained.

(1-c) Modification of Palladium Plate with Black Palladium:

In order to prepare a palladium platy electrode used for a hydrogenationapparatus in Comparison 2, first, a diaphragm type electrolysis cell wasassembled using a palladium plate having a thickness of 50 μm, whichserved both as a diaphragm and a cathode (surface area of palladiumplate: about 2.2 cm²). The electrolytic chamber side was filled with 15ml of a 0.3 M aqueous sulfuric acid solution, while the reaction chamberside was filled with 15 ml of a 28 mM PdCl₂ solution for modificationprepared by dissolving 74 mg of PdCl₂ in a 1 M aqueous hydrochloric acidsolution, respectively.

Then, using a platinum plate (size: 2 cm×2 cm) as an anode and thepalladium plate to be modified as a cathode, constant-currentelectrolysis was conducted at 50 mA/cm² for 1 hour to deposit palladiumblack to the palladium plate surface of the reaction chamber side.

(2) Dechlorination Treatment of Chlorinated Aromatic Compound:

The reaction chamber side of the hydrogenation apparatus 1 was filledwith 10 ml of a 0.1 M aqueous 2-chlorophenol solution prepared bydissolving weighed 1 mmol of 2-chlorophenol in distilled water. Theelectrolytic chamber side was filled with 15 ml of a 0.3 M aqueoussulfuric acid solution.

Then, using the palladium tube electrodes obtained in the aforementioned(1-a), (1-b) and the palladium plate electrode obtained in (1-c),constant-current electrolysis were conducted under the same conditions,that is, an electrolysis current value of 260 mA and an electrical flowof 2 F/mol, to dechlorinate 2-chlorophenol. After the reaction ends,respective solutions were collected and analyzedqualitatively/quantitatively with NMR, GC and GC-MS to check a generatedamount of corresponding phenol and, at the same time, to compare andevaluate yields and current efficiencies. The results are shown in FIG.5.

As shown in FIG. 5, it was confirmed that the hydrogenation apparatus 1in which the palladium tube electrode obtained in (1-a) was used(Example 7) and the hydrogenation apparatus 1 in which the palladiumtube electrode obtained in (1-b) was used (Example 8) had very highyield of phenol as a generated product and current efficiency ascompared to the hydrogenation apparatus in which the palladium platyelectrode obtained in (1-c) was used (Comparison 2).

Accordingly, it was confirmed that the hydrogenation apparatus 1 of thepresent invention using the palladium tube electrode was an effectivehydrogenation apparatus as compared to the conventional one.

Further, the inner surface area of the palladium tube electrodesobtained in (1-a) and (1-b) were 7 cm², and surface area of thepalladium platy electrode obtained in (1-c) was 2.2 cm². Thus,calculation of current efficiency per unit area gave 10%/cm² for thepalladium tubular electrode in Example 8, and 3.6%/cm² for the palladiumplaty electrode in Comparison 2. Accordingly, it was confirmed that thehydrogenation apparatus 1 of the present invention is superior also inthe current efficiency per unit area.

TEST EXAMPLE 1

Using the hydrogenation apparatus 1 of the present invention,4-chlorotoluene and 2-chlorophenol, which are chlorinated aromaticcompounds, were dechlorinated.

(1) Preparation of Chlorinated Aromatic Compound Solution:

Two kinds, 4-chlorotoluene and 2-chlorophenol, were used as thechlorinated aromatic compound. Each was weighed by 1 mmol, which wasdissolved in a solvent (methanol for 4-chlorotoluene, distilled waterfor 2-chlorophenol) to prepare 10 ml of a 0.1 M solution, respectively.

(2) Electrolytic Dechlorination Treatment:

An electrolytic dechlorination apparatus employing the hydrogenationapparatus 1 was used in a constant-current electrolysis at a currentdensity of 50 mA/cm², while using a platinum wire as an anode and thepalladium tube electrode having been modified with palladium black(surface area: 7 cm²) obtained in the aforementioned (1-a) as a cathodein a 0.3 M aqueous sulfuric acid solution. Using the electrolyticdechlorination apparatus, dechlorination treatment was conducted, inwhich the solution prepared in (1) was circulated inside the palladiumtubular electrode three times at a flow rate of 0.8 cm³/min with apressure feed pump.

Then, while defining the number of times for circulating the solution inthe palladium tubular electrode as number of cycles, relation betweenremaining ratio of the remaining chlorinated aromatic compound and thenumber cycles was measured and evaluated. The results are shown in FIG.6. Qualitative/quantitative analyses were conducted with GC and GC-MS,and generation of corresponding toluene (for 4-chlorotoluene) and phenol(for 2-chlorophenol) was confirmed.

As shown in FIG. 6, in each case where a 4-chlorotoluene or2-chlorophenol solution was used, the remaining ratio of generatedtoluene or phenol decreased along with proceeding of the cycle. Fromthis result also, it was confirmed that the hydrogenation apparatus 1 ofthe present invention is excellent in dehalogenation treatment(hydrogenation) of halogenated aromatic compounds.

INDUSTRIAL APPLICABILITY

The present invention can be used advantageously, for example, as ahydrogenation apparatus for use in hydrogenating unsaturatedhydrocarbons, halogenated compounds, long chain hydrocarbons and thelike, and as a method for hydrogenating the same.

1. An apparatus for hydrogenating an organic compound, comprising: areaction cell to which an electrolytic solution is supplied; and ananode and a cathode arranged in the reaction cell, wherein the cathode(i) is made of a material comprising a hydrogen storage material, and(ii) is arranged as a tubular member so that the organic compound to betreated circulates inside the cathode, and wherein the electrolyticsolution provides hydrogen from the cathode at the time of theelectrolysis and the hydrogen is consumed by the organic compound in thehydrogenation inside the cathode.
 2. The organic compound hydrogenationapparatus according to claim 1, wherein the hydrogen storage material ispalladium.
 3. The organic compound hydrogenation apparatus according toclaim 1, wherein the cathode is formed by treating an inner surface ofthe tubular member with the hydrogen storage material.
 4. The organiccompound hydrogenation apparatus according to claim 3, wherein thesurface treatment is a formation of palladium black on the inner surfaceof the cathode by an electrolytic reduction treatment of palladiumchloride.
 5. The organic compound hydrogenation apparatus according toclaim 1, wherein the cathode is formed by filling an inner part of thetubular member with the hydrogen storage material.
 6. The organiccompound hydrogenation apparatus according to claim 1, wherein the anodeis placed within the reaction cell and outside the tubular cathodemember.
 7. The organic compound hydrogenation apparatus according toclaim 1, wherein the electrolytic solution is selected from the groupconsisting of potassium hydroxide, sodium hydroxide, sulfuric acid, andhydrochloric acid.
 8. A method for hydrogenating an organic compound tohydrogenate the organic compound comprising: by using a reaction cellhaving an anode and a tubular cathode made of a hydrogen storagematerial, applying voltage between the anode and the cathode toelectrolyze an electrolytic solution existing between the anode and thecathode; and circulating the organic compound as the object to betreated inside the tubular cathode to hydrogenate the organic compound.